\begin{tabular}{l*{3}c}
\hline\hline
 & (1) & (2) & (3) \\
\hline
age1910\_census&28.8&27.9&0.9*\\
&[1.3]&[1.3]&(0.4)\\
\hline
Observations & 18 & 32 & 50 \\
\hline\hline
\end{tabular}
